However, NASA was quick to point out that the greenery gain occurring in the northern hemisphere thanks to frontrunners like China and India doesn't offset the rampant deforestation occurring in some parts of the tropics. While there are an estimated 3.04 trillion trees on the planet—about 422 for every human!—we're cutting down up to 15 billion a year to make way for infrastructure and agriculture, harvest materials like palm oil, and create consumer goods.

Trees do a whole lot more for humans than just provide some shade (though it turns out they do that even better than we initially thought). A single one can absorb as much as 48 pounds of carbon dioxide annually, making them a key ally in fighting climate change, and entire forests protect the land from erosion and improve water and soil quality.

Beyond that, trees are just fascinating. While there's still a lot to learn about them, we know that trees can actually "speak" with each other thanks to an underground system of minerals and chemical reactions, sharing valuable nutrients and warnings of incoming threats. The oldest ones have been around for thousands of years, and science is now racing to preserve their knowledge by cloning old-growth forests threatened by climate change. Needless to say, the world could use a lot more tree huggers.

How you can help keep our green spaces alive and well this Arbor Day.

This year, The Arbor Day Foundation launched its most ambitious goal yet: The nonprofit will plant 100 million trees around the world, recruiting 5 million volunteers in the process, by 2022.

"If ever there was a time for planting trees, it's now," Dan Lambe, president of The Arbor Day Foundation, told a crowd of onlookers and corporate partners when announcing the initiative on New York's High Line last month. If all goes to plan, Time for Trees will remove 578,000 tons of chemical pollution from the air—enough to fill 70,000 Goodyear blimps. If you're in the U.S., head to their tree map to see planting events happening in your state.

If you don't want to get your hands dirty, consider donating to the cause instead. Give to The Arbor Day Foundation; check out TreeEra, a subscription service where paying $12/month will plant 100 trees in your name annually; or support apparel companies that are greening the Earth. At outdoor brand tentree, they plant 10 trees for every item sold (25 million so far!), while fashion brand Amour Vert puts a tree in the ground for every T-shirt sold.